1. Field of the Invention
The present invention relates to the use of an antibody for the detection and/or quantification and/or isolation of basophils and/or mast cells and/or of the precursor cells of basophils and/or mast cells and/or of a surface structure of said cells.
The invention further concerns                a method for studying allergies;        a method for providing hematopoietic precursor cells that can differentiate into mast cells or basophils;        a substantially pure population of basophils and/or mast cells and/or of the precursor cells of basophils and/or mast cells; as well as        a reagent for binding said cells.        
2. Related Prior Art
Antibodies with which basophils and mast cells, in the mature state thereof, can each be detected, each individually, are known.
In hematopoiesis, also called blood formation, lymphoid and myeloid precursor cells arise from pluripotent stem cells in bone marrow. The lymphoid precursor cells give rise to T- and B-lymphocytes, while the myeloid precursor cells give rise to either erythrocytes, megakaryocytes, basophils, eosinophils, neutrophils, monocytes, or as-yet unknown precursor cells from which mast cells develop. Basophils, eosinophils, and neutrophils are together referred to as granulocytes. After hematopoiesis, basophils are present in the blood, while mast cells are present in tissues. In adults, hematopoiesis takes place in bone marrow.
Basophils and mast cells are multifunctional effector cells which participate in allergic and inflammatory reactions. Despite their similar biochemical and functional properties, basophils and mast cells are different cell types which both—like eosinophils—derive from CD34-positive precursor cells.
Distinguishing among the various cell types in the bone marrow and blood, and assigning them to various stages of differentiation, is an essential part of everyday clinical practice. For example, in order to diagnose blood-formation disorders it is necessary to determine the number of cells of each specific cell type, and if possible also their respective stages of differentiation.
In addition, the analysis of blood cells and blood precursor cells in the bone marrow is important in the diagnosis of leukemias. The number, type and stage of the cells are utilized to classify or allocate the type of leukemia, and to decide as to an appropriate therapy. Allocation of leukemia is based on the one hand on the clinical course of the disease, and on the other hand on the degree of maturation and the lineage of the pathologically altered leukocytes. This requires, however, determination of the cell type and status of both the healthy and the degenerate cells contained in a sample from a patient.
Up to now, these analyses are being performed under the microscope based on the morphology of the cells, after staining with conventional staining methods, for example Pappenheim staining or May-Grünwald-Giemsa staining, and by manual counting. Modern methods for the evaluation of bone marrow biopsies or blood samples use antibodies that recognize specific antigens as markers for certain cell types and stages. The antibodies and the recognized antigens, respectively, can then be automatically detected using standard methods such as ELISA (enzyme-linked immunosorbent assay) or flow cytometry (FACS: fluorescence-activated cell sorting).
Only a few antibodies which specifically recognize intact basophils are presently known, however. One of these antibodies is the antibody Bsp-1, which reacts with basophils but not with tissue mast cells (Bodger, M. P. et al., Blood 69 (1987), 1414). The CD117-reactive antibody YB5B8 recognizes mast cells and hematopoietic precursor cells (Ashman et al., Blood 78 (1991), 30).
DE 197 08 877 C1 describes the fact that antibody 97A6 binds specifically to megakaryocytes but not to thrombocytes.
No antibody is hitherto known, however, to simultaneously recognize basophils, mast cells, as well as their precursor cells.